HOUSTON — At first, all forensic anthropologist Sharon Derrick had to solve the mystery of ML73-3349 was the body of an unidentified boy, found dead more than 35 years ago, the voluminous police files from a decades-old serial killings and a desire to give a name to the nameless victim.

Now, two years after she first began the search, ML73-3349 has a name: Randell Lee Harvey. And Harvey's family has the answer they've waited a generation to have.

Derrick unraveled the mystery using a combination of high-tech science and old-fashioned detective work.

When she started, she knew that ML73-3349 was one of three still-unidentified victims of notorious Houston serial killer Dean Corll and his two teenage accomplices, who had tortured and killed 27 young boys in the early 1970s.

ML73-3349 was found on Aug. 8, 1973, in a makeshift grave in a Houston boat stall, where 17 of Corll's victims had been buried. It was the day that Corll was shot and killed by accomplice Elmer Wayne Henley.

Ever since, three victims who couldn't be identified had been in a refrigerated storage unit at the Harris County Medical Examiner's Office. ML73-3349 had been shot in the head.

Derrick also had a possible name: Harvey was a boy who had been reported missing in March 1971 and lived in the Houston neighborhood where the killers lurked. Harvey, a skinny boy with an unusual overbite, had been 15 when he vanished.

"The name Randy Harvey kept popping up in missing persons reports. I knew it was a name we should follow," Derrick, a forensic anthropologist with the Harris County Medical Examiner's Office, said Thursday.

For two years, Derrick scoured through police records and case files, searching for more clues that could lead her to the boy's identity. The medical examiner's office created anthropological and biological profiles of the victim, detailed enough to form an image of who he might have been.

He would have been white, between 15 and 20, about 5-foot-8 to 6-foot-1 and thin. A belt found near his remains was buckled to fit a lean 30-inch-waist.

Just like Randy Harvey.

In the paperwork, Derrick found more trails leading her toward Harvey. His name also turned up on a list of boys police believed might have been victims of Corll, and in other leads in the serial killing investigation.

Next, Derrick set out to find Randy Harvey's relatives. Not an easy task. Decades had passed. People who might have known the family in Houston had moved or passed away. His mother had remarried and changed her last name and that of Harvey's two sisters.

Finally, Derrick spotted a newspaper article about a member of their family. She called that person, who led her to the two sisters, Donna Lovrek and Lenore McNiel.

Their mother, Frances Conley, died more than 10 years ago, never knowing what had happened to her son. His sisters never stopped searching for their brother, but had always feared the worst. This week, they were still in shock.

"We are still going through our grieving stage. It's a little hard to describe how we're feeling right now," Lovrek said Wednesday night.

In May, the sisters submitted DNA samples, which were sent to the University of North Texas Center for Human Identification for comparison to samples taken from ML73-3349.

The process was slowed when the remains of the unidentified victim failed to provide enough DNA loci - a fixed position on a chromosome markers - for a good comparison, Derrick said. New more advanced tests were then conducted.

After several months, the results finally came back. Mathematically inconclusive.

A full DNA profile could not be garnered from the bones of ML73-3349, Derrick said. The mitochondrial DNA was a match, but was also a common profile shared by about 1 in 13 whites.

The victim and Harvey's sisters also shared a number of alleles - genetic markers- in their nuclear DNA. But again, they were common profiles.

However, the findings did not rule out the possibility that the unidentified boy was Harvey, Derrick said.

Instead, she explained, "they were weakly, gently supportive."

Derrick and colleagues studied the findings: the DNA tests, the profiles, the circumstantial evidence.

The first time she met McNiel, Derrick said she stopped in her tracks. McNiel's chin and that of ML73-3349 were strikingly similar.

Harvey and the unidentified victim also shared that pronounced overbite.

Harvey was known to carry a plastic pocket comb, and wear square-toed boots, similar to the items found with the victim. Harvey's sisters also seemed to recognize a blue jacket that belonged to the victim, and had known at least two of the identified victims.

Harvey disappeared from his neighborhood around the time Corll and his accomplices first began to prey on boys from that area. ML73-3349's body had been buried alongside victims killed during that time frame.

In addition, Derrick had spoken to David Owen Brooks, one of Corll's teenage accomplices, and shown him the drawing of a facial reconstruction of the unidentified victim. Brooks could not recall the boy's name, but described him as a "tall skinny kid" and drew a map leading to the house where Harvey and his family had lived.

Brooks and Henley are serving life sentences for their roles in the murders.

Using the DNA results and other evidence, the Harris County Medical Examiner's Office had also ruled out other possible candidates who fit the profile of Corll's victims, said Jennifer Love, director of the forensic anthropology division.

That left Randy Harvey.

Last week, authorities officially identified ML73-3349 as Randell Lee Harvey, ending his three decades in limbo.

"It took a few months, but we wanted it to be right. For the family, it's good for them to know, but it's hard for them to have concrete evidence. So that makes me sad," said Derrick. "I'm just very glad to be able to return him to his family."

Derrick is still working to determine the identities of the other two boys.

Copyright 2015 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.